JPH02114553A - Lead frame and method for manufacturing semiconductor devices using the same - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a lead frame and a technology for manufacturing a semiconductor device using the lead frame, and in particular, to a method of manufacturing a lead frame and a semiconductor device using the same. It's about technology.

[Conventional technology]

Regarding lead frames, for example, Japanese Patent Application Laid-Open No. 1983-1995
There are descriptions in JP-A No. 173 and JP-A-55-21128.

JP-A-52-95173 discloses semiconductor pellets (
In order to solve the problem of thermal stress being applied to the die pad due to the difference in thermal expansion coefficient between the pellet (hereinafter referred to as the pellet) and the lead frame, the pellet may crack or the pellet may peel off from the die pad. describes a technique for absorbing thermal stress by forming square holes or multiple round holes.

Additionally, Japanese Patent Application Laid-Open No. 55-21128 describes a technique in which the die pad is supported by arranging the suspension leads at the four corners of the die pad in order to improve the strength of the suspension leads that support the die pad. .

Incidentally, in recent years, with the spread of IC cards and ultra-thin electronic devices, development of semiconductor devices having an ultra-thin package structure to be mounted on these devices is progressing.

Regarding the ultra-thin package structure mentioned above, for example, see Mitsubishi Electric Corporation, published in December 1987, "Triple x
-(TRIPLE^)N (described in 118J).

The ultra-thin package structure described in the above document has V
S OP (Very Small 0utline
The package has a package structure of 1ml11, which is less than 2 times the thickness of the conventional SOP.

Further, a pellet having a thickness of 400 μm is sealed in the package, and the pellet and the inner lead are connected via a wire. Furthermore, in order to prevent the upper end of this wire from being exposed from the top surface of the package, the die pad on which the pellet is mounted is placed below the leads.

[Problem to be solved by the invention]

However, according to studies conducted by the present inventors, it has been found that the package structure described in the above-mentioned document has the following problems.

That is, the above document (rTRIPIJ A Nα18
When forming an ultra-thin package with a thickness of 1 m11 or less as described in ``11'' or less using the transfer molding method, the mold cavity is extremely narrow, so the fluidity of the resin injected into the cavity may be affected. decreases,
Voids are likely to occur at the interface between the die pad and the resin.

In order to prevent this, it is necessary to use a low-viscosity resin to improve its fluidity, and to equalize the flow rate of the resin flowing inside the cavity above the pellet and below the die pad.

However, when forming an ultra-thin package using the lead frame described in JP-A-55-21128, the die pad is placed higher than the inner lead surface in order to prevent the upper ends of the wires from being exposed from the package. Since the lead frame must be placed downward, when the lead frame is inserted into the mold during molding, the gap between the die pad and the lower mold becomes narrower than the gap between the pellet and the upper mold.

For this reason, more of the resin injected into the cavity flows onto the pellet having a wide gap than under the die pad where the gap is narrow. That is, the resin flowing above the pellet flows faster than the resin flowing below the die pad, and the pressure of the resin flowing above the pellet and below the die pad becomes uneven. Then, the resin flowing on the pellet pushes down on the die pad, stopping the flow of resin under the die pad, resulting in defects such as voids occurring under the die pad or the die pad being exposed from the bottom of the package. However, the manufacturing yield of the package decreases.

On the other hand, in the technique disclosed in JP-A-52-95174, a hole is formed in the die pad and the bottom surface of the pellet is exposed, so the resin flow in that part is improved by reducing the thickness of the die pad. However, this technology does not take into account the fluidity and filling properties of the resin flowing under the pellet, so as the thickness of the package becomes thinner, the flow rate and pressure of the resin flowing over the pellet and under the die pad must be equalized during molding. It becomes difficult to obtain the effect of

Such problems become even more pronounced when the pellet size is large.

The present invention has been made in view of the above-mentioned problems, and its purpose is to provide a technology that can improve the yield of manufacturing semiconductor devices having an ultra-thin package structure. .

Another object of the present invention is to provide a technique that can improve the reliability of a semiconductor device having an ultra-thin package structure.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Means to solve the problem]

A brief overview of typical inventions disclosed in this application is as follows.

In other words, the invention according to claim 1 is arranged such that when molding the pellet, the resin injected into the cavity from the gate of the mold flows along the flow direction of the Guipad on which the pellet on which a predetermined integrated circuit is formed is mounted. This is a lead frame structure in which an extending opening is formed.

The invention according to claim 2 is a lead frame structure in which the goo pad and the suspension lead are divided by an opening extending in the direction in which resin injected into the cavity from the gate flows when molding the pellet. .

The invention according to claim 3 is a method for manufacturing a semiconductor device using the lead frame according to claim 1 or 2.

[Effect]

According to the invention as claimed in claim 1, when molding a pellet using this reed framer, the flow path of the resin flowing below the pellet is secured by the opening, so that the fluidity of the resin flowing below the pellet is improved. In addition, the gap between the lower surface of the pellet exposed through the opening and the lower die and the gap between the upper surface of the pellet and the upper die can be made approximately equal.

As a result, when molding the pellets, the flow velocity and pressure of the resin flowing above and below the pellets are approximately equal, so that generation of voids and deformation of the goo pad can be effectively prevented.

According to the invention as claimed in claim 2, when molding pellets using this lead frame, the openings are formed not only in the Gui pad but also in the hanging lead, so that from the gate where resin is injected to the Gui pad. Since a wider flow path for the resin is ensured between the two, the fluidity of the resin is further improved.

According to the third aspect of the invention, when molding pellets using these lead frames, the flow path for the resin flowing below the pellet is secured by the opening, so that the fluidity of the resin flowing below the pellet is improved. In addition, the gap between the bottom surface of the pellet exposed through the opening and the lower mold can be made almost equal to the gap between the top surface of the pellet and the top mold, so that the upper and lower parts of the pellet can be The flow rate and pressure of the resin flowing through and can be made approximately equal,
As a result, the generation of voids and the deformation of the Guipad can be effectively prevented, and the manufacturing yield of the semiconductor device I can be improved.

[Embodiment 1] FIG. 1(a) is a plan view of a main part of a lead frame used in a method for manufacturing a semiconductor device which is an embodiment of the present invention. Figure 1 (a
) is a sectional view taken along the IB-IB line of FIG. 2(a), and FIG.
), FIG. 2(b) is a sectional view taken along line I[A-IIA of FIG. 1(a), and FIG. a)～(company)
is a sectional view of a main part of a mold used in a method for manufacturing a semiconductor device,
FIG. 4 is a sectional view taken along line IB--IB in FIG. 1(a), showing a semiconductor device manufactured using this lead frame.

The lead frame 1a used for manufacturing the semiconductor device of Example 1 shown in FIGS. 1(a) and 1(b) is, for example, a QF P
(Quad Flat Package) type semiconductor device.

This lead frame 1a includes, for example, a rectangular Gui pad 3 on which pellets 2 are mounted, hanging leads 4 arranged at the four corners of this Gui pad 3 and supporting the Gui pad 3, and radially arranged around the Gui pad 3. multiple leads 5
, a dam piece 6 which connects each lead 5 and surrounds the Gui pad 3, and a frame part 7 which surrounds these parts and consists of an outer frame part 7a1 and an inner frame part 7b.

The suspension lead 4 is bent so that the guide pad 3 is placed below the lead 5, as shown in FIG. 1 et al. This is to prevent the upper end of the wire 8, which will be described later, from being exposed from the upper surface of the package.

In the lead 5, the outside of the dam piece 6 is called an external lead, and the inside is called an internal lead.When the product is manufactured, the internal lead is sealed in the mold part 9, and the external lead is sealed from the side of the mold part 9. It protrudes outward to constitute an external terminal.

A guide hole 10 is punched out in the outer frame portion 7a by a press or the like and serves as a guide during transportation and positioning of the lead frame 1a.

The lead frame 1a has a plurality of unit frames constituted by the above-mentioned parts arranged in the direction in which the outer frame part 7a extends, for example seven series, which are integrally formed by pressing or the like, and the material thereof is as follows. For example, it is made of 4270 mm, and its thickness is, for example, 150 μm.

The Guibad 3 of the lead frame 1a has an opening 1
1a is formed with an opening, and the Guibad 3 is divided into two by the opening. This opening 11a is used as a gate (Fig.
The cavity K (shown in FIG. 3(a)) extends along the flow direction of the resin injected into the cavity K (shown in FIG. 3(a)). The opening 11a ensures a flow path for the resin flowing below the pellet 2, as shown in FIG. 1 et al.

In addition, since the openings 81B11a divide the Guibad 3 into two, for example, when moisture in the resin constituting the mold part 9 evaporates and expands during solder reflow, the stress generated in the Guibad 3 due to this vaporization expansion is absorbed by the pellet 2. 1/2 of
The size can be reduced to the same size as molded pellets.

Next, the method for manufacturing the semiconductor device of Example 1 is shown in FIG.
), (b), and FIGS. 3(a) to (ω).

First, the pellet 2 is bonded onto the Guibad 3 in which the opening 11a is formed using an adhesive 12 made of, for example, silver paste, and the adhesive 12 is cured at, for example, 180° C. (FIG. 2(a)). At that time, for example, if a curing method is used in which heating is performed gradually in an open furnace installed in a clean room, the film thickness of the adhesive 12 can be reduced to, for example, about 10 to 30 μm. The thickness of the pellet 2 is, for example, 400 μm, and the upper surface thereof is the integrated circuit forming surface. Furthermore, since the adhesive 12 needs to be thin, a material with low foaming property is selected.

Next, using a wire bonding device (not shown),
A wire 8 made of, for example, a gold wire with a diameter of 25 μm is bonded between the pellet 2 and the lead 5 (Fig. 2(b)
)). At that time, in order to prevent the upper end of the wire 8 from being exposed from the package 1 in the molding process described later, it is necessary to set the height (h) from the upper surface of the pellet 3 to the upper end of the wire 8 to a predetermined height. .

Thereafter, an extremely thin polyimide resin (not shown) is applied to the upper surface of the pellet 2. This is to prevent moisture in the resin constituting the mold portion 9 from penetrating into the integrated circuit, and to prevent the surface of the integrated circuit from being damaged by the filler in the resin.

Next, the process of forming the mold part 9 on the lead frame 1a on which the pellet 2 is mounted will be explained with reference to FIGS. 3(a) to 3(d).

A lead frame 1a loaded with mass and pellets 2 is placed at a predetermined position in a mold 13 for transfer molding.

Upper mold 13a inside the cavity of this mold 13
The gap between the lower die 13b and the lower die 13b is, for example, 1fffffi.

At this time, since the Guibad 3 has an opening 11a, the gap A between the upper part of the pellet 2 and the upper die 13a,
The lower part of the bellet 2 and the lower mold 13b exposed from the opening 11a
and the gap B becomes approximately equal.

Next, the preheated tablet-shaped resin 1 is placed in the pot 14.
Insert 5. This resin 15 is, for example, a silicone-modified epoxy resin filled with a filler such as phosphoric acid to have a coefficient of thermal expansion close to that of silicone, and the viscosity at the time of molding is, for example, 1×10”P (poise ) It is a low viscosity resin with the following.

Subsequently, the plunger 16 is lowered to release the molten resin 1.
5 is injected into the cavity K via the runner 17 and the gate G (Fig. 3 et al.)).

At this time, as described above, the gap A between the upper part of the pellet 2 and the upper mold 13a and the gap B between the lower part of the pellet 2 exposed from the opening 11a and the lower mold 13b are approximately equal, as shown in FIG. As such, the flow velocity of the resin 15 flowing above the pellet 2 and the flow velocity of the resin 15 flowing below the pellet 2 exposed from the opening 11a are approximately equal.

That is, the resin 15 flowing above and below the pellet 2
Since the pressure is almost uniform, the Gui pad 3 is
The resin will not be pushed down or pushed up (the resin will be filled sufficiently).

In this manner, the resin 15 is sufficiently injected into the cavity and is heated and cured for a predetermined time (FIG. 3(C)).

After the resin 15 injected into the cavity K has hardened, the mold 13 is opened and the lead frame 1a is taken out.
The hammer mold part 9 is completed (FIG. 3(d)).

Thereafter, the lead frame 1a is cut at a predetermined location, and the leads 5 are bent, for example, into a gull wing shape, thereby manufacturing the QFP type semiconductor device 18 shown in FIG. 4.

As described above, according to the first embodiment, the following effects can be obtained.

(1), ! To die pad 3 of J-de frame la,
When forming the mold part 9, from the gate G to the cavity K
Since the aperture 11a is formed to extend along the flow direction of the resin 15 injected into the resin 15, the fluidity of the resin 15 flowing below the pellet 2 exposed from the aperture 11a is improved.

(2) When forming the mold part 9, the gap B between the upper part of the pellet 2 and the upper die 13a and the lower part of the pellet 2 exposed from the opening 11a and the lower die 13a are almost equal. , resin 1 flowing above and below the pellet 2
The flow rate of resin 15 becomes almost equal, and the pressure of resin 15 also becomes almost uniform.

(3) According to (1) and (2) above, when forming the mold part 9, unlike the conventional technique, the die pad 3 is pushed down by the resin 15 flowing above the pellet 2,
The occurrence of voids and the exposure of the die pad 3 from the lower surface of the mold part 9 can be effectively prevented. (4)
, (1) and (2) above improve the filling properties of the resin.

(5) Since the die pad 3 is divided into two parts through the opening 11a, the thermal stress applied to the die pad 3 is dispersed, and cracks in the mold part 9 caused by this thermal stress can be effectively prevented. .

(6) According to (1) to (4) above, the thickness is, for example,
The mold portion 9 of lw can be formed with high yield, and the manufacturing yield of semiconductor devices is improved.

(7) According to (1) to (5) above, a semiconductor device including a highly reliable ultra-thin mold part 9 can be obtained.

[Embodiment 2] FIG. 5 is a plan view of a main part of a lead frame used in a method of manufacturing a semiconductor device according to another embodiment of the present invention.

In the lead frame 1b of Example 2, the goo pad 3 and the suspension lead 4 are divided by the opening part 11b extending along the direction in which the resin 16 injected from the geyser G flows when forming the mold part 9. has been done. That is, the die pad 3 and the hanging leads 4 are connected to the opening 11.
b into die pads 3a, 3b and suspension leads 4a, 4b, respectively.

According to the second embodiment, when forming the mold part 9, the resin 15 injected into the cavity from the gate G is poured into the opening 11b extending between the suspension leads 4a and 4b and between the die pads 3a and 3b. Since the flow path of the resin 15 is sufficiently secured without being obstructed by the suspension lead 4, the fluidity of the resin 15 flowing below the pellet 2 is further improved.

Other than this, the same functions and effects as in the first embodiment can be obtained.

The invention made by the present inventor has been specifically explained based on Examples above, but the present invention is not limited to Examples 1 and 2, and can be modified in various ways without departing from the gist thereof. Needless to say.

For example, the shape of the opening formed in the die pad is not limited to that in Example 1.2, and other shapes may be used as long as the opening is formed along the direction in which the resin flows during molding. It's okay.

That is, for example, the opening 811 of the lead frame lc shown in FIG. It may be comb-shaped like llc.

Further, it may be rectangular like the opening lid of the lead frame lid 3 of the lead frame lid shown in FIG.

Further, the material of the lead frame in the above embodiment is 4270
However, the material is not limited to this, and may be, for example, a copper alloy plated with tin-nickel.

In the above description, the invention made by the present inventor was mainly applied to a method for manufacturing a QFP type semiconductor device, which is the field of application that formed the background of the invention, but the invention is not limited to this, and for example, T Q F P
(Thin Quad Flat Package) or T S OP (Thin S+nall
0utline Package) shape and 5OJ (button al
l 0utline J-1ead Package)
It can also be applied to a method of manufacturing a type of semiconductor device.

〔Effect of the invention〕

Among the inventions disclosed in this application, the effects obtained by typical inventions are briefly described below.

(1), that is, in the lead frame according to claim 1, the Gui pad on which the pellet is mounted has an opening extending along the flow direction of the resin injected into the cavity from the gate of the mold when molding the pellet. When the pellets mounted on the Guipad are molded, the holes ensure a flow path for the resin flowing below the pellets, and a gap between the exposed lower part of the pellets and the lower mold and the upper part of the pellets. Since the gap with the upper mold can be made almost equal, the flow velocity of the resin flowing above and below the pellet,
and the pressures become equal, and the Gouipad is prevented from being pushed down by the resin flowing above the pellets, thereby preventing the generation of voids and deformation of the Gouipad.

(2) Furthermore, in the lead frame according to claim 2, the gui pad and the hanging lead are divided by an opening extending along the direction in which resin injected into the cavity from the gate flows when molding the pellet. Because of this, openings are also formed in the suspension leads, so when molding pellets, a wider flow path for the resin from the gate where the resin is injected to the Gui pad is secured, and the resin liquidity will further improve.

(3) Therefore, according to the method for manufacturing a semiconductor device according to claim 3 using the lead frame according to claim 1 or 2, the manufacturing yield of a semiconductor device having an ultra-thin package structure can be improved. .

[Brief explanation of the drawing]

FIG. 1(a) is a plan view of main parts of a lead frame used in a method for manufacturing a semiconductor device according to an embodiment of the present invention, and FIG. 1(b) is a first view showing an opening of this lead frame. A cross-sectional view taken along the IB-IB line in Figure (a), Figure 2 (a) is
The sectional view taken along the IIA-IIA line in Figure 1(a), which shows the case where pellets are mounted on this lead frame, and the cross-sectional view taken along the line IIA-IIA in Figure 1(a), which shows the case where pellets are mounted on this lead frame. 3(a) to (6) are sectional views taken along the line IB-IB, and FIG.
A cross-sectional view taken along line IB-IB in FIG. 1(a) showing a semiconductor device manufactured using this lead frame, and FIGS. 5 to 7 show manufacturing of a semiconductor device according to another embodiment of the present invention. FIG. 3 is a plan view of main parts of a lead frame used in the method. 1a to 1d...Lead frame, 2...Semiconductor pellet, 3...Gui pad, 4...Hanging lead, 5...
・ ・Lead, 6 ・ ・Dam piece, 7 ・Frame part,
7a...Outer frame part, 7b...Inner frame part, 8...Wire, 9...Mold part, 10...Guide hole, lla~
lid...opening part, 12...adhesive material, 13...mold, 13a...upper mold, 13b...lower mold, 14...
Pot, 15...Resin, 16...Plunger 1
7...Runner 18...Semiconductor device, K...Cavity, G/Gate.

Claims (1)

[Claims] 1. A die pad on which a semiconductor pellet on which a predetermined integrated circuit is formed is mounted has an opening extending along the direction in which resin injected into the cavity from the gate of the mold flows when the semiconductor pellet is molded. A lead frame characterized by having a hole formed therein. 2. A lead frame comprising a die pad on which a semiconductor pellet on which a predetermined integrated circuit is formed and a suspension lead supporting the die pad, wherein the die pad and the suspension lead are connected to a gate during molding of the semiconductor pellet. A lead frame characterized in that the lead frame is divided by openings extending along the direction in which resin injected into the cavity flows. 3. A method for manufacturing a semiconductor device, characterized in that the lead frame according to claim 1 or 2 is used.